Spark plug



M. F. PETERS ETAL 2,357,602

Sept. 5. 1944.

SPARK PLUG Filed June 5, 1942 FIG.5.

FIG

TIME FIG. 8.

IN V EN TORS MELV/LLE F. PETERS, FRED 1. Mc CARTHY. BY 7 ATTORNEY Patented Sept. 5, 1 944 SPARKPLUG Melville F. Peters, Beltsville, Md., and Fred 1. McCarthy, New York, N, Y.

Application June 5, 1942, Serial No. 445,938

14 Claims.

The invention also consists in providing a copper sleeve with a wedge shaped member around the spindle shank in order to direct the component of forces when the powder is compacted, so as to close any passage and'thereby prevent gases from passing into the spark plug.

The invention also consists in equalizing the heat at the spark end, by the provision of a cutout, and a heat distributing sleeve on the spindle s Also the invention consists in providing a spark gap at one ,end of the spindle shank at the interior of the spark plug which has a distinct relation to the spark gap at the exterior end of the spark plug, means beingprovided to determine the size of the gap. Y

The invention contemplates as alternatives the use of a helical spring to surrounda mica sleeve enclosing the spindle shank, and then to be compacted with the powder; spaced conically shaped washers orrings to augment the compacting actionwhen the powder is compacted, and a conically shapedinsulating spacer resulting in a conically shaped space to assist the heat exchange action at the spark gap end of the spark plug. Either one or all of these may be used.

. The invention will be more fully described hereinafter, embodiments are shown in the annexed drawin8, andthe invention will be finally set forth in the claims.

In the accompanying drawin Fig. 1 is a vertical central section through an embodiment of our spark plug; a

Pig. 2 shows an enlarged fragmentarycentral section of the metallic powder portion of the embodiment showninFig. 1;

Fig. 3 is a fragmentary section showing-the force components;

Fig. 4 is a central section or the spark plug 'end, and embodying various alternatives;

' Fig. 5 is a central section at the top end of the spark plug shown in Fig. 1, showing the initial spark gap determinative of the spark gap-at the.

' of the spark plug of Fig. 1;

Fig. 'l is an electric diagram showing the relationship of the initial spark gap to the final M 8 9; n

curve A resulting from our improved invention.

Similar reference characters have been used to indicate like parts throughout the several views.

Referring to the drawing, and more particularly to Fig. 1, the usual'spark plug is there shown, with one improvement embodied therein; The present improvements consist in providing the central spindle shank III which terminates at its lower end at l2 at the exposed end of the spark plug, and which is cylindrical in shape. A cylindrical sleeve l3 of mica or the like, or a mica cigarette, extends along the. length of the spindle shank III. A sleeve ll! of mica or the like, is concentric with the mica cigarette. The

outer sleeve 18 terminates. at its upper end I! and is held to the body portion 20 of the upper shell by upsetting the body portion as shown, and the lower end of the sleeve [9 rests upona shoulder 2| of the lower shell. The upper and lower shells are connected by screw thread 2|. The lower shell 2| has a conical bore 22 and a filling of powder indicated by 23 fills the space circumferentially around the spindle shank l0 and The use'of the metallic powder around a portion of the insulating material or cigarette sleeve l3 provides a close packing and obliterates gas leakages and aids in the heat conductivity in the lower shell. The powder. is packed tightly and aids in the displacement of heat to the outer Above the compacted powder a se-- lower shell. ries of mica washers or rings II are compacted together, on the top of which an insulating ring I1 is provided, which is sligthly larger than the rings I! so that when compressed therein the rings I! are held in permanent position. Other fastening devices may be used.

In'Fig. 2 is shown an enlarged portion of part of Figure '1. copper powder, incombination with enclosures for the same, to enable such pressures to be applied to the powder that it appears to act as a fluid, and forms a solid. The enclosures consist of the interior ofthe shell, preferably of conical wall 22, and the exterior of thespindle shank l0, and a conically shaped member 59- to direct the forces in such a directionas to obtain a secure gas seal. The spindle shanklll is surrounded by a mica sleeve or mica cigarette II,

p Fig. 8 is a chart showing three curves, the 60 and also by a thin copper sleeve l3 preferably- The important step is the use of part of the cone shaped base member 59*. The

ofl'about where the mica washers are placed;

Or the washers and another sleeve added to assist in the filling and t; can then be withdrawn. The iriegularities of the exterior surface of the copper sleeve, and the irregularitiesof the interior surface of the metal of the casing (visible by magnification) are filled in by the small particles of powder and are forced closed by pressure, and "at the same time, the mica cigarette adjacent the copper sleeve is pressed against the spindle shank, in a manner that such particle pressure presses the mica intimately against the'exterior surface of the. spindle shank. The mica cigarette being somewhat pliable fills the ii regularities of the spindle shank and copper sleeve. The preliminary pressure applied gradually permits this orientation, and the further pressure consolidates these actions, to the extent that when the entire pressure action has been completed. there cannot be any return movement, the inherent energy applied holding the parts described in this close fitting relationship the powder having'become a solid. This is vfurthei accentuated by the inward component of the force ofthedownward axial pressure acting inwardly against I the outer surface of this spindle shank, thereby securing a still further positive anchorage. A

copper sleeve may terminate at the mica I stantially even and cool temperatures; The refractory material ring 50 of Fig. ,1 is of a size to determine the length of thespark gap V: or 46. Or thering in combination with other refractory' material, such as mica washers, may be used. The structureis arranged so that the member 5! is not too cold, and the sparking end of the spindle shank is not toohot. By equalining the rate of heat flow in the two members, the thermal qualities of the plug are greatly improved. In Fig. l, the spacing ring 50 is substantially cylindrical, but in Fig. 4, it is conical as at 50 in Fig. 4, in which case an airspace 60* results, which aids in increasing the surface flash over distances between the spindle head l2 and the part 52. Also, the shell is provided with a deep cut out 51, to keep 52 warm enough. Finally, the lower end of the spindle shank Hi from the end to where the copper powder filling ends gas tight seal' along the outer surface of the spindle shank and the inward surface of the shell is thereby provided.

vIn Fig. 3 is a, detail view: showing how the powder presses against the inclined wall 22, and

a component acts to transmitdownward force to. an angular force against the exterior of the spindle shank, which as stated is enveloped by the mica cigarette and thiscigare'tte is covered by the copper sleeve l3.

In Fig. 5 an enlarged view of the top of the spindle shank is shown. The top is cut away in the general or space 44. The conducting T-shaped member 4|, has its vertical leg refractory insulating L shaped tubing 43, hollow shape shown so as to form agap 42 surrounded by a axially, and the axial tube thereof seals into the' cut out gap 44 o-f the spindle. A washer 45 of metal 'also holds the mica washers IT in place, and

the washer 45 has its bore 45 surround the outer .cl-rcumference of the end ll! of the spindle shank ,Ill. The mica cigarette l3 terminates at its up- /per end with .below the end It. hi gap 44;

enables'the voltage at the sparking gap to build up more rapidly than if this series gap were not present. r

In Fig. 7 an electric diagram is shown to illustrate the formula which is applicable, to wit:

' sparking gap 46.

.series gap 44, and the gap V2 corresponds to the at the top has its outer peripheral portion ground off and replaced by a copper, sleeve, or preferably by a copper plating 59, which conducts the heat away from the tip end upwardly, and distributes it at a place where such distribu-' tion is harmless.

As an alternative, there is shown in Fig. 4, a

series of metal rings or washers 6U,"0f wedgeshaped cross-section, around which the powder flows, and also a, helical spring 6| to hold the mica cigarette, and as before explained, a minical member till 0f micaor ceramic instead of a cylindrical member 50, withan air space 50.

Either oneor all of these alternative features can be placed in the embodiment of Figure 1.

In Fig. 6, the depth of the cut out 51 prevents the device from fouling; the deeper the cut out test the mica cigarette from drawing gases from the engine, and it is placed in such a, manner that if it cracks, the pieces will not get into the engine W have described several forms of our invention, but obviously various changes may be made in the details "disclosed without departing from the spirit of the invention as set out in the following claims.

Whatisclaimed is:

1. In a spark plug. having a central spindle shank the end of which forms 'one terminal, a layer of compressed metallic powder surrounding said spindle shank, said compressed powder obstructing the passage of gases but assisting the passage of heat, a metallic sleeve with a wedgeshaped member surrounding said spindle shank, the wedge-shaped member being adapted to direct a component of force against said spindle shank.

2. In a spark plug having a central spindle shank the end of which forms one terminal, a

,.mica cigarette surrounding said spindle shank, a

time as the abscissa Y expenditure of the least time, much better than curves 3 or .C of the prior art.

Figs.--1, 4 and6 present views showing the sparking head. The important feature is to pro vide means to keep the metallic parts at subshank the end of which forms one layer of compressed metallic powder surrounding said-spindle shank and the mica cigarette, said compressed powder obstructing the passage of gases but assisting the passage of heat, a metallic sleeve with a wedge-shaped member surroundihg said spindle shank, the wedge-shaped member being adapted to direct the component'of force against said spindle shank, the lower end of the spindle shank being copper or other metal enclosedto conduct heat from the spark end inwardly of the spark plug.

--3. In a spark plug having a central spindle terminal, the

and an ins'ulating member determining the size of the gap,

said insulating member being conical and providing a conically shaped cooling space,

4. In a spark plug having a central spindle shank with a spark gap at its outer end, a mica cigarette surrounding the spindle shank, a wedgeshaped bore in the body of the spark plug, a wedge-shaped base member in said bore surrounding the mica cigarette, a copper sleeve surrounding said mica cigarette above the base member, a compacted powder in said bore compressed by high pressure to a solid fillin said bore andpressing against said wedge-shaped base member, copper sleeve, mica cigarette and spindle shank, and mica washers above said solid compact.

'5. In a spark plug having a central spindle shank with a spark gap at its outer end, a mica cigarette surrounding the spindle shank, a wedgesh'aped bore in the body of the spark plug, a wedge-shaped base member in said bore surrounding the mica cigarette, a copper sleeve surrounding said mica cigarette above the base member, a compacted powder in said bore compressed by high pressure to a solid filling said bore and pressing against said wedge-shaped base member, copper sleeve, mica cigarette and spindle shank, mica washersabove said solid compact, and a helicalsprlng around said mica cigarette.

6. In a spark plug having a central spindle shank with a spark gap at its outer end, a mica cigarette surrounding the spindle shank, a wedgeshaped bore in the body of the spark plug, a wedge-shaped base member in said bore surrounding the mica cigarette, a copper sleevesurrounding said mica cigarette above the base member, a compacted powder in said bore compressed by high pressure toa solid filling said bore and pressing against said wedge-shaped base member, copper sleeve, mica cigarette and spindle shank, mica washers above said solid compact, .a helical spring around said mica cigarette, and wedge-shaped rings compacted within said powder compact.

7. In a spark plug having an outer shell with a bore, a central spindle shank disposed centrally or the bore in spaced relationship to the bore of the outer shell, a lining member surrounding" said shank at least along a length corresponding to the bore of the shell, and a layer of solid connects ing material formed by pressure from a powder disposed between the shell bore and shank, said solid layer, shell and shank being substantially one mass to prevent the passage of gases, but permitting the passage of heat.

8. In a spark plug, a shank with a cutout at its spark gap end, a central spindle shank having an end to form a spark gap with the shell and having a cutout, and an. insulating member in said cutouts disposed transversely to the spark gap, thelength oi the cutouts and insulating member therein being' determinative oi the length separating the shell and spark gap."

9. In a spark plug, a .shellwith a cutout disposed longitudinally thereof, a central spindle spindle to form the having a cutout disposed longitudinally thereof,

the shell and spindle having ends to form a spark gap, an insulating material layer surrounding the spindle to insulate .the shell from the Spindle. and a second layer between the first layer and the spark gap to protect the-first layer from the effects of any gases 7 passing through the spark gap.

projection and liningthe walls of the bore to confine the spark between the end of the projection and bottom of the bore and prevent it from contacting with the walls of the bore.

11. In a spark plug, a shell having a bore, a central spindle shank the end of which forms one terminal, and spaced from the wall of said bore, a layer of solid metal pressed tightly against the spindle and wall of the bore, and substantially integral therewith, to prevent the passage of gases between the metal, spindle and layer, but permit the passage of heat, and means at the spark gap end of the shell and spindle consisting or a cutout in the shell forming a free space transversely across the spark gap formed by the shell and spindle, to enable the remaining part of the shell to distribute the heat in order to decrease the amount of heat passing through the layer of solid material.

12. Ina spark plug, an outer shell having a bore, a spindle spaced from the walls of the bore, a solid material pressed between the walls of {the bore and spindle to be substantially integral an insulating material sleeve surrounding said spindle from end to end thereof, a compacted powder in said bore compressed by high pressure to a; solid filling the space between the spindle sleeve and. wall 01' the bore in the shell, and pressed against said shoulder.

14. ,In a spark plug having an outer shell member with a cylindrical bore and with a spark plug terminal at one end thereof, a central cylindrical spindle shank terminating in another terminating spark plug terminal spaced 'from the firstnamed terminal, saidspindle disposed in spaced relationship within said shel centrally of its bore, said outer shell also having a conical cir- 6 member and t insulating\lining and shank being substantially one mass to prevent the passage oi. gases but cumierential wall adjacent said cylindrical bore;

an insulating member around the central spindle at least the axial length of the bore and the axial length of the conical wall leaving .a conical space between the insulating member and the shell member, alayer of solid metal in the space be-' tween the insulating member and said conical wall, and insulating means disposed against the top oi'the solid metal layer between the outer spindle, said shell, solid member,

permitting the passage of heat.

mvrun r. PETERS. man I. mommy. 

